Flashing red light

How to read it

The MUTCD says traffic facing a flashing circular red stops at the stop line, or before the crosswalk, or, where there is neither, at the point nearest the cross road where the driver can see traffic on it, and that the right to go on is then subject to the rules that apply after stopping at a STOP sign. The Uniform Vehicle Code, the model rules of the road, calls it a stop signal. The state manuals make the comparison directly: Pennsylvania’s says a flashing red light has the same meaning as a STOP sign, Florida’s says to treat it like a stop sign, and California’s says that after stopping a driver may go when it is safe. The light flashes 50 to 60 times a minute. This page describes the national standard and isn’t legal advice; the rules at a signal are set by state law and vary from state to state.

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Flashing red on some approaches or on all of them

A traffic signal switches to flashing operation when its conflict monitor detects a fault, and the MUTCD also lets some signals run in flashing mode at set times of day. Its guidance is a flashing yellow for the major street and flashing red for the other approaches, unless every approach flashes red. Intersection control beacons, flashing lights used at intersections where conditions do not justify a full signal, follow the same pattern: yellow on one route and red on approaches with STOP signs, or red on every approach where all of them have STOP signs. Pedestrian signals go dark while a signal is flashing. A flashing red stop beacon may also be mounted with a STOP, DO NOT ENTER or WRONG WAY sign.

Not the railroad crossing lights

The red lights at a railroad crossing are a separate device. The railroad flashing-light signal has two red lights side by side that flash alternately when a train is approaching or on the crossing. The MUTCD keeps the two apart: where an intersection beacon uses two red lights side by side, they flash together, so that they are not confused with crossing signals. The rules differ too. The Uniform Vehicle Code’s section on flashing signals says it does not apply at railroad crossings, which it governs separately. At a flashing red on the road a driver may go on after stopping; at a crossing, Pennsylvania’s manual says to proceed only after the signals have stopped and there is evidence no trains are approaching.

When the signal is dark

A signal with no lights at all, as in a power cut, is not a flashing red, but the manuals treat the two alike. Oregon’s says a flashing red or a dark signal is treated the same as a stop sign. Pennsylvania’s says a non-functioning signal is treated as a four-way STOP, and California’s and Florida’s say the same of a signal that is not working or out of order. Michigan’s says to come to a complete stop, yield to vehicles already at the intersection, and yield to the vehicle on the right when two arrive together.